Major contaminants from venting and hydrogen explosions at the Fukushima Daiichi nuclear reactors between 12 and 15 March 2011 were transported northwestward and deposited on soil and plants via precipitation. Surface soils and plant leaves were sampled at 64 sites in the Fukushima Prefecture. The highest concentrations of ¹³⁴Cs (84.4 kBq kg⁻¹) and ¹³⁷Cs (82.0 kBq kg⁻¹) in surface soils were observed at Nagadoro in Iidate village located 32 km northwest from the Fukushima Daiichi nuclear power plant. Furthermore, ¹³¹I, ¹²⁹Te, ^129mTe, ^110mAg and ¹⁴⁰La were detected in the same samples. Outer surface of plant leaves, such as bamboo, cabbage and grasses were highly contaminated at the high-dose rate areas of Tsushima and Minami-Tsushima in Namie town. Mugwort leaves that grew after the pollution event had extremely low concentration of radionuclides; however, the plant/soil radiocaesium ratio was 0.023±0.006. It is anticipated that decomposition of fallen leaves will promote recycling of radionuclides in the environment.

The March 2011 earthquake and tsunami resulted in significant damage to the Fukushima Daiichi Nuclear Power Plant (FDNPP) and the subsequent release of radionuclides into the ocean. Here, we investigated the spatial distribution of strontium-90 (⁹⁰Sr) and cesium-134/cesium-137 (^{134, 137}Cs) in surface seawater of the coastal region near the FDNPP. In the coastal region, ⁹⁰Sr activity was high, from 0.89 to 29.13 mBq L⁻¹, with detectable FDNPP site-derived ¹³⁴Cs. This indicated that release of ⁹⁰Sr from the power plant was ongoing even in May 2013, as was that of ¹³⁴Cs and ¹³⁷Cs. ⁹⁰Sr activities measured at open ocean sites corresponded to background derived from atmospheric nuclear weapons testing fallout. The FDNPP site-derived ⁹⁰Sr/¹³⁷Cs activity ratios in seawater were much higher than those in the direct discharge event in March 2011, in river input, and in seabed sediment; those ratios showed large variability, ranging from 0.16 to 0.64 despite a short sampling period. This FDNPP site-derived ⁹⁰Sr/¹³⁷Cs activity ratio suggests that these radionuclides were mainly derived from stagnant water in the reactor and turbine buildings of the FDNPP, while a different source with a low ⁹⁰Sr/¹³⁷Cs ratio could contribute to and produce the temporal variability of the ⁹⁰Sr/¹³⁷Cs ratio in coastal water. We estimated the release rate of ⁹⁰Sr from the power plant as 9.6 ± 6.1 GBq day⁻¹ in May 2013 on the basis of the relationship between ⁹⁰Sr and ¹³⁷Cs activity (⁹⁰Sr/¹³⁷Cs = 0.66 ± 0.05) and ¹³⁷Cs release rate.

Mamuju, Indonesia, is an area with high natural background radiation. This study assesses heavy metal content in soil samples from this area to determine the level of public and environmental hazard it presents. This study analyzes natural radionuclide elements using high purity germanium (HPGe) gamma spectrometry and performs heavy metals analysis using a flame atomic absorption spectrometry (FAAS). Moreover, pollution indices and descriptive analyses were used to assess heavy metal contamination in the environment and the correlation between heavy metals and radionuclides. The results demonstrate that soil samples in several areas of Mamuju contain a high concentration of the natural radionuclides ²²⁶Ra and ²³²Th, and that heavy metal concentrations in the soil decrease in the sequence Zn > Pb > Cr > Cu > Ni > Cd. This study revealed that soil samples from Mamuju are moderately contaminated. There was a strong positive relationship between ²²⁶Ra, ²³²Th, ambient dose equivalent rate, and Pb. Ecological risk index (RI) and cumulative pollution index (IPI) values in Mamuju are 2.05 and 125, respectively, which are possible hazards to human health as a result. Pb concentration in the Mamuju soil samples ranged from 109 to 744 mg kg⁻¹, exceeding the worldwide average of 27 mg kg⁻¹.